The present invention relates to a demodulator for an FS communication system used mostly for data transmission.
As well known in the art of data communication, the FS communication system is a kind of frequency modulation communication wherein digital signals "1" and "0" are represented by two different frequency carrier waves and these carrier waves are alternately transmitted. The transmitted signals in the FS communication are called "frequency shift signals (FS)". Demodulators at an FS signal receiving station are usually implemented with LC tuning circuits, zero-crossing detection techniques, etc. That is, these demodulators depend upon analogue technology.
Many approaches have been attempted to rearrange a variety of circuits in digitalized fashions because of the recent development of inexpensive, reliable and small-sized LSI's.
Accordingly, it is an object of the present invention to provide a demodulator digital LSI capable of digitally demodulating FS signals.